ملخص الدراسة:

Underspecification Theory(henceforth UT) is one of the controversial issues of Lexical Phonology . Ut is concerned with the theory of features and the specification of underlying segments; hovering mainly on the idea that features should be left unspecified if a lexical phonological rule would be capable of filling them in ,i.e. Underspecification pursues the omission of certain features in underlying representation and the specification of underlying segments. Dinnsen(1998:294) contends that the theory crucially distinguishes between these properties of underlying representations that must be specified and those that must be underspecified ,that is not specified. The underspecified properties, in this case, are filled in by rules of various types that express the predictable value of the property. Durand(1990:156) argues that there are two views on the specification account:1) a full specification account, and a partial specification account. The former type is concerned with the utterance of a value for each feature into a phonological matrix including the total set of distinctive features as high , low , back, round and voice. The latter approach leaves out some predictable features; the missing values would be then filled by redundancy rules, with the possibility that the contrast between two phonemes suspends in some contexts leading to the postulation of archiphonemes. In this case, UT is not just an attempt to achieve formal simplicity at the underlying level. At the basis of this approach lies an interest in a symmetrical segments or feature-values in languages, as it starts from the assumption that underlying specification should be as streamlined as possible and that redundancies should be extracted from underlying entries for distinctive features and all other aspects of phonological representations.